Despite Iran's efforts to jam satellite channels and the crackdown on satellite dishes, many Iranians -- according to some estimates more than half -- watch foreign satellite TV channels.

Even if satellite jamming is a useful tool in protecting Islamic values, it is not permissible under Islamic law if it poses a health threat.

That's according to an Iranian grand ayatollah who recently made a ruling on the issue following an inquiry by a Shi'ite news agency.

Shafaqna, whose Persian-language material is produced in Tehran, recently posed the question:

"Given the enemy's exploitation of satellite channels in order to [push forward] its goals against Islam, [and considering] the interests of the Islamic world and Islamic culture one the one hand, and on the other the jamming of these channels, which increases the risk of neurological disorders, heart arrhythmias and cardiac arrest, death of children and newborns, leukemia, multiple sclerosis, and incurable diseases and the silent death of Muslims and other citizens of Muslim countries -- are the transmissions of these permissible under Islamic laws or not and what is the verdict?"

Grand Ayatollah Musavi Ardebili, in a written response to Shafaqna, wrote, "If it is proven that jamming signals cause significant problems such as those mentioned in the question, then their transmission is not permissible."

The ruling, which was described as a "fatwa" by several popular news sites that reposted it, comes amid a long-running debate in the Islamic republic about the possible health effects of satellite jamming.

Iran is known to use jamming technology to prevent satellite transmissions of foreign-based television and radio channels in Iran. After Iran claimed to have downed a U.S. drone in 2011 after disrupting its communications system, the question arose whether Tehran had acquired or developed sophisticated jamming equipment, possibly including laser-burst technology that could target satellites.

But while little is known about the precise technology Iran employs to scramble satellite transmissions, Iranian newspaper reports and also some officials -- including Massoumeh Ebtekar, a former member of Tehran's city council and currently vice president -- have suggested that the practice could cause health problems for citizens.

"What we know is that these signals have an impact on people's health and the body's cells," Ebtekar was quoted as saying in 2012. "As an immunologist and researcher, I'd say that these signals could be the source of many illnesses."

In February, Iranian Health Minister Hassan Hashemi said that a committee was looking into whether jamming indeed poses a health threat. "The initial reports show that the existing jamming signals pose no physical harm, but the committee needs to carry out its investigation thoroughly," he said.

He also said that there were widespread "rumors" about jamming's effects and consequences on people's health, while adding that "most of the rumors have no scientific basis."

The inquiry by Shafaqna appears to reflect the concerns about the potential health hazards of jamming. In addition to Ardebili, the website asked two other clerics, Ayatollah Sohani and Ayatollah Shabiri Zanjani, about the permissibility of jamming. Neither had a straight-forward answer.

Sohani said it wasn't up to a jurist to make a ruling and that a judge could make a decision in such a case. Zanjani said that the answer to Shafaqna's question would depend on how negatively satellite broadcasts were influencing audiences on the one hand, and the extent of health dangers on the other.

The reports in Iranian media about the adverse effects of satellite jamming, including miscarriages and increased cancer rates, appear to largely rely on anecdotal evidence.

An unidentified World Health Organization representative told the Small Media Foundation in 2012 that, without knowing the exact strength of the jamming frequencies, it would be impossible to draw any conclusions about the health risks.

Iranian authorities are not transparent about their jamming efforts and the systems they use.

Ali Akbar Musavi, a U.S.-based rights activist and a former lawmaker who investigated jamming in Iran about a decade ago, says that at that time jamming centers were scattered in and around major cities and operated by "military bodies."

Musavi says Iran jammed satellite signals and also used "local jamming," by using trucks in specific locations to interfere with reception at the ground level. He says it is not clear what kind of jamming techniques authorities are using now.

Earlier this year, the United States reportedly waived sanctions on Iran's state broadcaster after it determined that "harmful satellite interference" was not currently emanating from Iran.

Musavi says officials should make public information about the bodies that currently conduct jamming and the techniques they use. "The concern is that mobile jamming stations could get close to people," he tells RFE/RL. The authorities "should announce whether they're observing international standards."

RFE/RL's Radio Farda is a target of Iran's jamming efforts. Radio Farda Director Armand Mostofi says that there has been no change to the extent of jamming faced by the Persian-language service since President Hassan Rohani came to power in 2013.

Despite Iran's efforts to jam satellite channels and the crackdown on satellite dishes, many Iranians -- according to some estimates more than half -- watch foreign satellite TV channels.

The authorities increase their jamming efforts during politically sensitive times, including at time of unrest.